The feeding apparatus of B. microplus is a primary tanned and secondary tanned (sclerotized) cuticular structure with segments of softer untanned cuticle. It begins as a channel between the hypostome and chelicerae and within the capitulum divides to give, ventrally the pharyngeal valve, pharynx and oesophagus and above these, the salivarium and paired salivary ducts. An extension of the hypostomal gutter and the membrane overlying it are continuous with the outer and inner walls of the pharyngeal valve. Anteriorly, the valve is flexible but posteriorly the walls have heavy sclerotized rods apposed to a sclerotized tooth projecting from the roof into the lumen. This more rigid posterior part curves ventrally and is supported by the alae. Dilator muscles are attached along the walls of the valve. The pharynx is a double Y-shape ({ie55-1}) in transverse section with circular closing muscles interspaced between stouter opening ones. The salivarium is a broad shallow tube bounded by the sub-cheliceral plate. The floor has flexible junctions to the plate, and muscles which pass to the alae may lower the floor to open the salivary channel. During drinking by larvae there is a repeated sequence of movements; pharyngeal valve open—pharynx open—valve closed—pharynx closed. When the valve opens the walls are tensed against the anchoring sheet formed by the alae and the sclerotized roof. Following muscular relaxation, elastic recoil forces the walls together just before the peristaltic closing movements of the pharynx begin.